Upstream Issue: https://github.com/karma-runner/karma/issues/1782
[mediawiki-core-qunit](https://integration.wikimedia.org/ci/job/mediawiki-core-qunit/) builds have been failing since [#56634](https://integration.wikimedia.org/ci/job/mediawiki-core-qunit/56634/).
~~This could be fixed with a downgrade I believe.
~~
[Console:](https://integration.wikimedia.org/ci/job/mediawiki-core-qunit/56634/console)
```
00:19:47 Running "karma:main" (karma) task
00:19:47 06 01 2016 00:19:47.138:INFO [karma]: Karma v0.13.10 server started at http://localhost:9876/
00:19:47 06 01 2016 00:19:47.167:INFO [launcher]: Starting browser Chrome
00:19:51 06 01 2016 00:19:51.718:INFO [Chromium 47.0.2526 (Ubuntu 0.0.0)]: Connected on socket /#e7Iz24mfR_FJ5dmQAAAA with id 6014961
00:20:01 ................................................................................
00:20:01 ................................................................................
00:20:05 ................................................................................
00:20:05 .................................................................
00:20:05 Chromium 47.0.2526 (Ubuntu 0.0.0): Executed 305 of 305 SUCCESS (7.557 secs / 7.238 secs)
00:20:05 Missing error handler on `socket`.
00:20:05 TypeError: Object [object Object] has no method 'forEach'
00:20:05 at disconnectBrowsers (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/lib/server.js:311:13)
00:20:05 at null.<anonymous> (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/lib/server.js:291:7)
00:20:05 at EventEmitter.emit (events.js:117:20)
00:20:05 at emitRunCompleteIfAllBrowsersDone (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/lib/server.js:256:12)
00:20:05 at null.<anonymous> (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/lib/server.js:278:9)
00:20:05 at EventEmitter.emit (events.js:117:20)
00:20:05 at onComplete (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/lib/browser.js:142:13)
00:20:05 at Socket.<anonymous> (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/lib/events.js:13:22)
00:20:05 at Socket.EventEmitter.emit (events.js:117:20)
00:20:05 at Socket.onevent (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/node_modules/socket.io/lib/socket.js:335:8)
00:20:05 at Socket.onpacket (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/node_modules/socket.io/lib/socket.js:295:12)
00:20:05 at Client.ondecoded (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/node_modules/socket.io/lib/client.js:193:14)
00:20:05 at Decoder.Emitter.emit (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/node_modules/socket.io/node_modules/socket.io-parser/node_modules/component-emitter/index.js:134:20)
00:20:05 at Decoder.add (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/node_modules/socket.io/node_modules/socket.io-parser/index.js:247:12)
00:20:05 at Client.ondata (/mnt/jenkins-workspace/workspace/mediawiki-core-qunit/src/node_modules/karma/node_modules/socket.io/lib/client.js:175:18)
00:20:05 at Socket.EventEmitter.emit (events.js:95:17)
00:21:05 06 01 2016 00:21:05.859:WARN [Chromium 47.0.2526 (Ubuntu 0.0.0)]: Disconnected (1 times), because no message in 60000 ms.
00:21:05 Chromium 47.0.2526 (Ubuntu 0.0.0): Executed 305 of 305 DISCONNECTED (1 min 7.573 secs / 7.238 secs)
00:21:05 Fatal error: Object [object Object] has no method 'forEach'
00:21:05 Build step 'Execute shell' marked build as failure
00:21:05 [PostBuildScript] - Execution post build scripts.
```